Current athletic shoes are a combination of many elements which have specific functions, all of which must work together for the support and protection of the foot during an athletic event. The shoes are designed to provide a unique and specific combination of traction, support and protection to enhance athletic performance. Shoes are designed for specific sports and also to meet the specific characteristics of the user. For example, athletic shoes are designed differently for heavier persons than for lighter persons, differently for wide feet than for narrow feet, differently for high arches than for lower arches, and so forth. Some shoes are designed to correct physical problems, such as over-pronation, while others include devices, such an ankle supports, to prevent physical problems from developing.
Athletic shoes are divided into two general parts--an upper and a sole. The sole is attached to the bottom of the upper and provides traction, protection and a durable wear surface. The upper is designed to snugly and comfortably enclose the foot. In a running or jogging shoe, the upper typically terminates below the ankle bones and will have several layers including a weather and wear resistant outer layer of leather or synthetic material, such as nylon, and a soft padded inner liner for foot comfort. In athletic shoes designed for sports which require the athlete to make sudden and rapid lateral movements, such as in basketball, football, tennis or ice hockey, the upper frequently extends up to or above the ankle bones (the medial and lateral malleoli). Such shoes are referred to as three-quarter height or high top shoes.
Attaining a proper fit around the ankle bones in three-quarter height and high-top athletic shoes has been a problem because the uneven contour around the ankle bones varies from person to person. The typical prior art technique for fitting the upper around the ankle bones has been to line the ankle portion of the upper with a relatively soft foam material. However, since no two persons have precisely the same ankle bone configuration, the foam material only approximates a customized fit.
The use of adjustable air-inflated bladders in the ankle portion of an upper is also found in the prior art. The most frequent use of such bladders is found in ski boots wherein the upper is relatively inflexible and the air bladders are designed to embrace the ankle and lower leg and provide a restraining force against the foot. Such air bladders typically form rigid vertical columns along the medial and lateral sides of the foot and leg, thereby restricting movement of the foot. While such restriction of motion is desirable in a ski boot, it interferes with required foot motion in athletic shoes designed for athletic activities such as basketball, football and tennis. West German Patents 2,365,329 and 2,308,547 disclose examples of such air bladders used in ski boots. As seen in FIGS. 4 and 5 of these patents, a separate tongue bladder and ankle bladder are provided, with the ankle bladder having cut out areas avoiding the malleoli and achilles tendon. However, as is typical in ankle bladders used in prior art ski boots, the ankle bladder forms relatively rigid vertical columns.
U.S. Pat. No. 3,758,964 ('964) relates particularly to ski boots and shows a bag member enclosed therein. Two chambers A and B are illustrated in FIG. 16 of the '964 patent. Chamber B forms an uninterrupted column of pressurized gas from the top to the bottom on both the medial and lateral sides; it also completely covers the malleoli. Chamber A, while not extending the entire vertical height, does form a restrictive column adjacent the malleoli. A different configuration for chambers A and B is depicted in FIG. 17 of the '964 patent. Chamber B therein forms a less substantial vertical column, but one would still form along the outer perimeter, anterior of the malleoli. Chamber A also forms a vertical column posterior to the malleoli. FIG. 18 of this patent shows two small chambers B and a large chamber A. While chambers B cover the malleoli thereby restricting movement, chamber A forms vertical columns posterior to the malleoli. These vertical columns are formed near the malleoli and thereby have a stiffening effect which restricts plantar and dorsi flexion of the foot. Although these restrictive vertical columns in covering of the malleoli are preferred for activities such as skiing where the foot must be secured in the boot, they actually reduce the athlete's performance in sports such as basketball, football, soccer, tennis and running. Studies have shown that an athlete's performance can be reduced when restrictions are placed on his plantar and dorsi flexion. See John F. Robinson et al., "Systematic Ankle Stabilization and the Effect on Performance," Medicine and Science in Sports and Exercise, Vol. 18, No. 6, 1986, pp. 625-628.
Examples of other shoes having bladders or similar arrangements include those disclosed in U.S. Pat. Nos. 1,313,924, 2,086,389, 2,365,807, 3,121,430, 3,469,576, 3,685,176, 3,854,228, 4,232,459, 4,361,969 and 4,662,087, in French 1.406.610 patent and PCT Publication WO 90/09115. See also U.K. application 2.111.821.A. Some of these designs include bladder placement which actually interferes with the fit of the foot in the shoe, some are not volume or pressure adjustable to provide a customized fit, some interfere with cushioning components of the shoe, some restrict the movement of the foot and some interfere with the pronation/supination action of the foot. None of them meets today's rigorous athletic standards, and none of them is especially well-suited for use in high top ice skates, basketball or tennis shoes.
An example of a recent inflatable shoe is THE PUMP basketball shoe available from Reebok. This shoe has a round molded rubber bulb pump on the tongue of the shoe and having an opening at one end and a one-way valve at the other end. A piece of tubing is stuck into that opening at one tubing end and the other tubing end is stuck into a flange attached to the shoe bag, which originally used reticulated foam therein, and held therein by adhesive. A duck-bill type of valve in the flange allows air to flow only from the bulb pump to the bag and not the other way. The deflation valve is a piece of tubing with one end welded to and sticking out of the bladder. The other tubing end is hooked to a molded plastic housing, and a metal-pin Schraeder-type tire deflation valve is secured in the housing.
A number of problems with this bladder-pump assembly have been experienced. Adhesives used to secure the pump and bag components together are often not reliable and are difficult to work with. For example, the adhesives have shelf lives, are affected by moisture, require clean application surfaces and can be contaminated when being mixed. If the pump is subjected to considerable flexing during athletic activity, the tube tends to pop out of it. To fix it requires that the shoe be torn open, and thus as a practical matter it is not repairable by the consumer. When excessive strain is applied, failure can also occur where the pump tubing enters the flange. Different size bladders for different shoes disadvantageously require different lengths of this comparatively rigid tubing. The deflation valve has numerous moving and connection parts and thus is unnecessarily likely to fail, difficult to assembly and bulky.
Reebok International Publication No. WO 90/04323 shows a shoe with an inflatable bladder wherein foam is provided in the pump cavity. This foam reduces considerably the pump volume, however. The inflatable bladder is in the tongue of the shoe, according to that disclosure, the reduce bumps caused by the shoe laces. This placement can reduce plantar and dorsi flexion, since the tongue area is thereby made thicker and can tend to bunch up when the foot is bent. While this is not a problem with rigid ski boots, it can reduce performance in athletic shoes. The tubes connecting the bladder chambers can by their connections provide possible failure areas.
L. A. Gear has recently introduced a line of shoes called THE REGULATOR which use a pump. The bladders are sewn into the tongue only, however. The bladder film comprises a 0.20 inch PVC heat sealed to form chambers. The pump comprises a rubber bulb pump with valves in the front and back, and a PVC extension tube welded to the bladder and cemented to the pump. The release valve is hooked on the pump nozzle end and is released by a sliding instead of a pushing action, and thus could be prone to accidental release. A one-way valve is press-fit into the back of the pump and locked on mechanically with a metal clip. This bladder when inflated tends to push down on the foot restricting plantar and dorsi flexion thereof.